1. Field of the Invention
The present invention relates to an evapo-control valve to be used in a combustion engine of a land vehicle.
2. Prior Art
An evaporated gas (hereinafter referred to as an evapo-gas) in a fuel tank is discharged to an atmosphere by providing an evaporated control valve (hereinafter referred to as an evapo-control valve) in a pipe which connects a fuel tank to a canister.
That is, the evapo-gas in the fuel tank is supplied to the canister by opening and closing the evapo-control valve provided in the pipe depending on the pressure in the fuel tank.
FIG. 9 shows a conventional evapo-control valve comprising a casing 82 having a canister side connecting port 81 and a collar 84 having a fuel tank side connecting port 83, wherein the casing 82 and the collar 84 form a space therein. In the space, there are provided a closing valve 85 which is openable from the fuel tank side to the canister side, a spring 86 which presses the closing valve 85 against the collar 84 and a check valve having a shell type valve 87 which is provided in the central portion of the closing valve 85 and openable from the canister side toward the fuel tank side.
According to the conventional evapo-control valve, when the pressure inside the fuel tank rises to a reference value due to generation of the evapo-gas, the gas pressure exceeds the resilience of the spring 86 to thereby open the closing valve 85 so that the evapo-gas in the fuel tank is supplied to the canister. As a result, it was possible to prevent a pressure in the fuel tank from rising and to let the evapo-gas for going off into the canister.
When the pressure in the fuel tank is reduced due to consumption of the fuel and the cold weather, the shell type valve 87 is open so that the atmosphere is introduced from the canister into the fuel tank. As a result, the pressure in the fuel tank equals to the atmospheric pressure thereby preventing the fuel tank from deforming.
Since the closing valve 85 is not open until the pressure in the fuel tank rises to a prescribed value according to the conventional evapo-control valve, the evapo-gas is not supplied to the canister until it rises to the prescribed value so that the evapo-gas, which remains in the fuel tank, is discharged to the atmosphere when the filler cap is open.
When the spring 86 having less resilience is employed to close the closing valve 85, there was a problem in that the liquid fuel is apt to be introduced into the canister because the liquid fuel opens the closing valve 85 when the liquid fuel is supplied to the fuel tank.